(* An ocamlyacc-style, or Menhir-style, parser requires access to the lexer, which must be parameterized with a lexing buffer, and to the lexing buffer itself, where it reads position information. *)(* This traditional API is convenient when used with ocamllex, but inelegant when used with other lexer generators. *)type('token, 'semantic_value) traditional =(Lexing.lexbuf -> 'token)->Lexing.lexbuf -> 'semantic_value
(* This revised API is independent of any lexer generator. Here, the parser only requires access to the lexer, and the lexer takes no parameters. The tokens returned by the lexer may contain position information. *)type('token, 'semantic_value) revised =(unit -> 'token)-> 'semantic_value
(* --------------------------------------------------------------------------- *)(* Converting a traditional parser, produced by ocamlyacc or Menhir, into a revised parser. *)(* A token of the revised lexer is essentially a triple of a token of the traditional lexer (or raw token), a start position, and and end position. The three [get] functions are accessors. *)(* We do not require the type ['token] to actually be a triple type. This enables complex applications where it is a record type with more than three fields. It also enables simple applications where positions are of no interest, so ['token] is just ['raw_token] and [get_startp] and [get_endp] return dummy positions. *)val traditional2revised:
('token -> 'raw_token)->('token ->Lexing.position)->('token ->Lexing.position)->('raw_token, 'semantic_value) traditional ->('token, 'semantic_value) revised
(* --------------------------------------------------------------------------- *)(* Converting a revised parser back to a traditional parser. *)val revised2traditional:
('raw_token ->Lexing.position ->Lexing.position -> 'token)->('token, 'semantic_value) revised ->('raw_token, 'semantic_value) traditional
(* --------------------------------------------------------------------------- *)(* Simplified versions of the above, where concrete triples are used. *)moduleSimplified : sigval traditional2revised:
('token, 'semantic_value) traditional ->('token *Lexing.position *Lexing.position, 'semantic_value) revised
val revised2traditional:
('token *Lexing.position *Lexing.position, 'semantic_value) revised ->('token, 'semantic_value) traditional
end